Effect of route of administration and age on the pharmacokinetics of amikacin administered by the intravenous and intraosseous routes to 3 and 5-day-old foals.

This study explores the effectiveness of two routes of administering amikacin, an antibiotic, to baby horses — through their veins and directly into their bone marrow. The results suggest that the two routes are essentially equal in terms of efficacy and that older foals metabolize the drug faster than younger ones.

Objective and Methodology

• The research aimed to investigate how well the intraosseous (i.o.) method of drug administration — injected directly into the bone marrow — works in foals compared to the traditional intravenous (i.v.) approach.
• Amikacin sulfate (an antibiotic used to treat bacterial infections) was used for the study.
• A total of 6 healthy foals were selected for the study, and each one was given the drug at 3 and 5 days old, using both methods (i.o. and i.v.).
• The research was designed as a cross-over study, meaning that each foal received both types of administration.

Findings and Conclusions

• The study found that amikacin was immediately and completely absorbed, whether administered via the i.o. or i.v. route.
• The maximum concentrations of the drug in the blood (after 3 minutes of administration) were not significantly different between the two methods.
• A 2-compartment open pharmacokinetic model — a mathematical model that describes how the body processes a drug — was fittingly used to describe the body’s handling of amikacin for both methods.
• No significant differences were found in major pharmacokinetic variables, like how fast the drug was absorbed or cleared from the body, between the two methods.
• However, the research found variations in drug clearance values, which were not related to the route of administration, but were greater with age. The 5-day-old foals cleared the antibiotic faster than the 3-day-old foals.
• The researchers also reported that they did not encounter any technical difficulties while administering the drug directly into the foal’s proximal tibia, the bone bearing the most weight.
• Minor soft tissue swelling at the site of intraosseous injection was observed, but it completely removed within 1-2 months.

From this research, it can be concluded that the intraosseous method of drug administration is equally effective as the intravenous route in neonate foals, although the age of the foals may affect how quickly their body processes the drug.